The subject invention is directed to new and novel regio-regular, functionalized hydrocarbon polymers (i.e., polymers bearing oxygen and/or nitrogen atom in pendent functional groups) and methods of forming the same. Specifically, the present invention is directed to regio-regular polymers having substantially all viciral (i.e., head-to-head) configuration of functional groups pendent from the polymer backbone chain. The polymers are formed by ring-opening metathesis polymerization of a C.sub.7 -C.sub.12 cycloalkene having a vicinal pair of functional groups pendent from ring carbon atoms. The resultant polymer may then be hydrogenated to provide a substantially straight chain alkylene polymer having head-to-head pendent functional groups periodically distributed along the polymer chain. These polymers exhibit enhanced gas barrier and/or tensile properties and have other properties which make them useful in forming films and other articles.
High pressure, free radical polymerization has been an important industrial technique for providing a wide variety of polymer products. The technique requires an initiator, such as a peroxide, to initiate the chain growth. A variety of homopolymers and copolymers have been formed by this technique. However, the monomeric units forming the copolymers are normally randomly distributed along the polymer chain backbone and the polymer has a high degree of short and long chain branching due to side reactions. Even when forming functional group containing homopolymers, there is a high degree of head-to-tail arrangement of the functional groups with respect to the polymer chain. Head-to-tail orientation of consecutive mers of a vinyl polymer can be simply represented as: --CH.sub.2 --CHX--CH.sub.2 --CHX--, while head-to-head orientation is represented as: --CH.sub.2 --CHX--CHX--CH.sub.2 --, where X represents functional groups. Normally, only small amounts of head-to-head arrangement of functional group containing monomeric units may be found in polymers formed by free radical polymerization.
More recently, polymerizations have been conducted with Ziegler-Natta or metallocene catalyst. However, polymerization by this technique is generally limited to non-functionalized monomers, such as olefins suitable for forming polyethylene, polypropylene and the like.
Ring opening metathesis polymerization (ROMP) has been studied during the past two decades using early transition metal complexes. These studies were conducted on strained cyclic olefins to provide polymers of controlled molecular weight and structure. For example, cyclobutenes have been the subject of ROMP to provide poly(butadiene) or polybutenamer. It has been well documented that this polymerization is driven by the high strain energy of the cyclobutene ring (29.4 kcal/mol). In Makromol. Chem. 1962, 56, 224, Dall'Asta et al first reported the ROMP of cyclobutene using TiCl.sub.4 /Et.sub.3 Al to provide a polybutadiene having high cis configuration. Other two component ROMP catalyst systems have been used to polymerize cyclobutene and its derivatives. In addition, one component catalysts, such as Ph(MeO)C.dbd.W(CO).sub.5, PhC.dbd.WCO.sub.5 and RuCl.sub.3 were successfully used in similar polymerizations.
However, in none of the above cases was a living polymerization observed. Polymerization reactions are considered living when the reaction is capable of proceeding substantially in the absence of termination steps and chain transfer reactions. When the rate of polymer chain initiation occurs faster than chain propagation the living system affords polymers of controllable molecular weight and narrow polydispersity. Living polymerization systems are also capable of synthesizing block copolymers (see Noshay et al, Block Copolymers, Academic Press, N.Y. 1977).
The area of functionalized polyolefins has received great attention recently. The fine tuning of the type and amount of functional groups, as well as the location of the functional groups on the polymer backbone to optimize the properties which can be achieved by a particular polymer has been of great interest. Functionalized alkylene polymers have conventionally been prepared by free-radical or anionic polymerization of vinyl monomers. However, such polymerization techniques of functionalized vinylically unsaturated monomers have provided polymers with a preponderance of head-to-tail configuration of the monomeric units, with a high degree of branching and, where copolymerization is conducted, the monomeric units are generally randomly distributed along the polymer backbone chain. Due to the electrophilic nature of transition metal catalysts, such as metallocene or conventional Ziegler-Natta catalysts, towards a large variety of functional groups, the synthesis of polyolefins with polar functional groups has met with only limited success.
Recently, the ROMP of certain substituted strained cyclic and bicyclic olefins has been accomplished. 3-Methylcyclobutene and 3,3-dimethylcyclobutene as well as norbornene have been ring opened and polymerized. The ROMP of cyclobutenes which are substituted with acid or alcohol functional groups has only been accomplished indirectly. For example, highly strained 3,4-disubstituted cyclobutenes bearing benzyl-protected methylene ether or ester pendent groups have been subjected to ROMP followed by post-polymerization removal of the protection group to provide a polyallyl alcohol homopolymer product.
With the development of other metathesis initiators, such as those described by Nguyen et al in JACS 1992, 114, 3974 and JACS 1993, 115, 9858; by Schwab et al in JACS 1996, 118, 100; Schrock et al, in JACS 1990, 112, 3875; Fox et al in Inorg. Chem. 1992, 31, 2287; and by Grubbs et al, in U.S. Pat. No. 5,312,940, one has achieved metathesis polymerization of certain cyclic olefin compounds which contain functional groups. However, such polymerizations were not living polymerizations and, therefore non-linear, high dispersity polymer products were achieved. Further, the monomers were highly strained compounds, such as norbornene derivatives which provide a cyclic moiety within the polymer chain or, alternately, were mono functional acyclic olefins which provided polymers having the functional groups randomly located along the polymer chain.
It has been highly desired to provide a linear polyolefin polymer having pendent functional groups uniformly distributed in a controlled manner along the polymer backbone. Such polymers are believed capable of providing polymer films and articles having uniform structure and highly desired properties.